//HW3

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
pthread_mutex_t mlock = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t mcond = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t condv = PTHREAD_COND_INITIALIZER;
int box[4];
int count = 0;

void *gcd(void *nums);
void *work(void *tum);

void *gcd(void *nums)
{
  int a, b, d, org1, org2;
  char pair[20];

  sscanf(nums, "%d, %d", &a, &b);
  org1 = a;
  org2 = b;

  box[3] = -1;
  int c = -1;
  int cnt = 0;

  while(c != 0)
    {
      if(b > a){
	d = a;
	a = b;
	b = d;
      }
      pthread_mutex_lock(&mlock);
      box[0] = a;
      box[1] = b;
      box[2] = -1;
      
      while(box[2] < 0){
	pthread_cond_signal(&condv);
      }

      cnt++;
      a = box[2];
      b  = box[1];
      c = box[2];

      pthread_mutex_unlock(&mlock);
    }

  count++;
  printf("Thread ID:%d \tGCD of %d & %d: %d after %d tries\n", pthread_self(), org1, org2, b, cnt);

  pthread_exit(NULL);
}

void *work(void *tnum)
{
  int test;
  test = (int)tnum;
  while(count < (int)tnum)
    {
      pthread_cond_wait(&condv, &mcond);
      box[2] = (box[0] % box[1]);
    }
}

main(int argc, char** argv)
{
  if(argc == 1 || argc % 2 != 1)
    {
      printf("give me pairs of numbers and I will give you GCDs\n");
      exit(0);
    }

  else
    {
      clock_t c0, cl1;
      time_t t0, t1;

      t0 = time(NULL);
      c0 = clock();

      printf("begin wall: %d\n", (long)t0);
      printf("begin clock: %d\n", (int)c0);

      int a1, b1, c1;
      int check = 1;
      int tnum = (argc/2);
      pthread_t threads[tnum];
      pthread_t worker;
      int rc, t;
      char pair[20];

      if(pthread_create(&worker, NULL, work, (void *)tnum)){
	printf("ERROR");
      }
      else{
	printf("Creating Worker thread\n");
      }

      for(t = 0; t < tnum; t++)
	{
	  box[3] = 1;
	  a1 = atoi(argv[check++]);
	  b1 = atoi(argv[check++]);

	  sprintf(pair, "%d, %d", a1, b1);

	  printf("Creating thread\n");
	  rc = pthread_create(&threads[t], NULL, gcd, (void *)&pair);
	  
	  if(rc){
	    printf("ERROR");
	    exit(-1);
	  }

	  while(box[3] != -1);
	}

      for(t = 0; t < tnum; t++)
	{
	  pthread_join(threads[t], NULL);
	}
      printf("ALL DONE\n");

      t1 = time(NULL);
      c1 = clock();

      printf("\nEND wall time:\t%1d\n", (long)(t1));
      printf("END clock time:\t%f\n", (float)(cl1));

      exit(0);
    }
}